1. Field
Embodiments of the inventive concepts relate to titanium oxide having a hexagonal column shape, a method of fabricating the same, a solar cell including the same, and a method of fabricating a solar cell including the same. More particularly, embodiments of the inventive concepts relate to hexagonal column-shaped titanium oxide fabricated using oxalic acid and sodium dodecylbenzenesulfonate (SDBS), a method of fabricating the same, a solar cell including the same, and a method of fabricating a solar cell including the same.
2. Description of the Related Art
A solar cell is a photovoltaic energy conversion system that converts light energy emitted from the sun into electric energy.
A silicon solar cell uses a P-N junction diode for the photovoltaic energy conversion. However, silicon used in the silicon solar cell should have a high degree of purity and a low number of defects in order to prevent premature recombination of electrons and holes. Since these technical requirements increase costs of used materials, a preparation cost of the silicon solar cell per unit of power is high. In addition, since only photons, energies of which are equal to or higher than a band dap ban gap, are used to generate a current, the silicon of the silicon solar cell should be doped to have a band gap that is low as possible. However, electrons excited by blue light or ultraviolet light have excessive energies due to the low band gap, and thus they may not be used to generate a current but may be consumed as heat. Furthermore, a P-type layer should be sufficiently thick in order to increase possibility of capturing a photon. However, since the thick P-type layer increases possibility that excited electrons are recombined with holes before reaching a P-N junction, the efficiency of the silicon solar cell remains in the range of about 7% to about 15%.
To solve these problems, Korean Patent Publication No, 10-2013-0102667 (Application No 10-2012-0023636) discloses a dye-sensitized solar cell using a semiconductor electrode layer including metal oxide nanotubes containing metal nanoparticles, and Korean Patent Publication No. 10-2009-0124094 (Application No. 10-2008-000050097) discloses a quantum dot-sensitized photovoltaic cell of which a photovoltaic conversion efficiency is improved by forming a CdS light absorption layer at a porous titania layer by a spray pyrolysis technique and by forming a TiO2 nanoparticle in a TiCl4 solution.